Yamaha might say that it was the company's RX-1 that made the idea of a performance 4-stroke snowmobile acceptable. We only partially agree. Yes, to us the RX-1 made 4-stroke snowmobiles acceptable, but it was the Yamaha Apex that made 4-stroke snowmobiles believable.
Indeed, if not for online feedback referring to the RX-1 as the 'Yamaha RX-1-Ton,' the Apex nomenclature may never have surfaced. But because of the hefty negative online forum feedback about the RX-1's weight, Yamaha decided to do away with the old name and find a new descriptor for what would be a much more sprightly sled with rider-forward ergonomics, more 4-stroke engine response and, yes, less weight.
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2009 Yamaha Apex GT Review on Snowmobile.com